1. Field of the Invention
The present invention relates to a recording apparatus and method for recording information such as images or characters on a recording medium and a removing claw to be used for the apparatus, and more particularly to a recording apparatus having a removing mechanism provided close to a rotary drum for recording, a recording method and a removing claw to be used for the apparatus.
2. Description of the Related Art
In a conventional recording apparatus, a laser beam is irradiated from an optical head onto a recording medium fixed to a rotary drum for recording (which will be hereinafter referred to as a “recording drum”) or a recording plane, thereby recording images and characters. In this case, a toner sheet having a thermal melting, thermal adhesive or sublimate coloring material layer (photothermal conversion+toner layer) formed on a support such as a permeable PET (polyethylene terephthalate) base and an image receiving sheet having an image receiving layer for receiving a toner to be transferred are used for the recording medium, and the toner sheet is heated corresponding to image and character data and a heated portion of the toner layer is transferred onto the image receiving layer of the image receiving sheet. Thus, an image is recorded on the image receiving sheet.
A toner sheet having each of colors of K (black), C (cyan), M (magenta) and Y (yellow) or a toner sheet having each of colors of gold, silver, brown and gray can be used. For example, a full color image can be obtained by using a toner sheet having four colors of KCMY.
The toner sheet and the image receiving sheet which are to be used have different structures and characteristics depending on the uses respectively, and the details thereof have been described in JP-A-4-296594, JP-A-4-327982 and JP-A-4-327983 according to the application of the present applicant.
FIG. 3 is a diagrammatic sectional view showing a color image recording apparatus 30 according to a conventional example.
In FIG. 3, the color image recording apparatus 30 according to the conventional example serves to obtain a full color image by using a toner sheet having four colors of KCMY, and comprises a recording medium feeding section 32, a recording drum 34, a recording medium fixating/releasing mechanism 36, a laminate mechanism 38, an exposing head 40, a control section 48, a removing mechanism 42, a paper feeding section 44, a laminate section 46, a removing section 50 and a tray section 52.
In the color image recording apparatus 30 according to the conventional example, the recording medium fixing/releasing mechanism 36 fixes an image receiving sheet 10 fed from the recording medium feeding section 32 onto the recording drum 34, and the laminate mechanism 38 pressurizes, heats, presses and laminates a toner sheet 11 fed from the recording medium feeding section 32 onto the image receiving sheet 10. When the exposing head 40 heat mode exposes a laminated product of the image receiving sheet 10 and the toner sheet 11 to record an image as a latent image, the removing mechanism 42 removes the toner sheet 11 from the image receiving sheet 10 fixed onto the recording drum 34, and transfers and develops the image of the toner sheet 11 recorded as a latent image onto the image receiving sheet 10. Consequently, an image is formed on the image receiving sheet 10.
For example, thus, the image receiving sheet 10 in which images having four colors of K, C, M and Y are accurately registered and the removing, transferring and developing operations are carried out is removed from the recording drum 34 through the removing mechanism 42, and is laminated and closely bonded to a paper 14 in the laminate section 46. Then, the image receiving sheet 10 is removed from the paper 14 in the removing section 50. Consequently, a full color image can be obtained as a hard copy.
On the other hand, there is also a high speed one path printer capable of forming a color image through a one-time processing in addition to the recording method of repeating exposure and development for four colors. More specifically, recording is carried out, by means of a light source having a plurality of wavelengths, on a monosheet sensitive material to be independently sensitized with a plurality of wavelengths respectively, and development is then performed through a heat source. With such a structure, four-color exposure is carried out on a sensitive material having a four-color and four-layer structure through one-time exposure by means of an exposure head capable of performing laser irradiation having corresponding four wavelengths. Therefore, a high speed processing can be achieved.
FIG. 3 is a view showing a structure of the monosheet sensitive material printer, (a) being a perspective view and (b) illustrating a principle. As shown in FIG. 3(a), a sheet obtained by cutting, into a print size one by one, a plural-wavelength photosensitive material having a photothermal developing layer shown in FIG. 3(b) is used as a recording medium 3 and is wound and fixed onto a rotary drum 22 for recording. The rotary drum 22 for recording is rotated in a direction of an arrow and two-dimensionally scans and exposes a transfer material 3 on the recording medium 3 through a four-colored laser beam of an image while moving through a moving stage 24 from an optical head 21 capable of carrying out laser beam irradiation having four wavelengths shown in FIG. 3(b) in a direction orthogonal to the direction of rotation of the rotary drum 22 for recording. If the recording medium 3 which has been exposed like an image is thermally developed, an unexposed portion is colored so that a color print of the monosheet is obtained by the high speed one path method.
Next, an operation will be described. An example of the recording medium to be used is shown in FIG. 3(b). A sensitive material for reacting to a light provided with layers having different wavelengths to generate colors of (Y, M, C and K) is superposed in multilayers on a transparent support such as a light transmission PET through an intermediate layer respectively, and the recording medium is fixed onto the rotary drum 22 for recording.
The optical head 21 to be used can simultaneously irradiate a light having a plurality of (four-colored) laser wavelengths such as Y: 410 nm (LD) or 405 nm (SHG), M: 532 nm or 526 nm (SHG), C: 680 nm or 660 nm (LD) and K: 830 nm or 780 nm (LD) which correspond to four colors of Y, M, C and K. The LD represents a laser diode, and the SHG represents a Second Harmonics Generator (secondary harmonics generator) and serves to obtain a light having a wavelength ranging from 1064 nm to 532 nm, for example.
The laser head is constituted as shown in FIG. 3(b) to irradiate a laser beam having four wavelengths from a total reflecting prism AP to the recording medium 3 through each dichroic prism. A dichroic mirror can freely select a transmission wavelength and a reflection wavelength depending on a method of depositing an interference film. A dichroic mirror for LD1 reflects a light having a wavelength of 830 nm and transmits others and a dichroic mirror for LD2 reflects a light having a wavelength of 630 nm and transmits a light having a wavelength of 830 nm.
The laser beam having four wavelengths transmitted from the total wavelength reflecting prism shown in FIG. 3(b) is moved through the moving stage 24, thereby scanning and exposing the recording medium 3 of the rotary drum 22 for recording through the laser beam having four wavelengths. A latent image is independently recorded for each color with a laser beam having a wavelength (a wavelength ranging from 300 nm to 1100 nm) corresponding to an absorption wavelength of a photothermal developing layer for each color. For example, laser recording is carried out in the vicinity of a wavelength of approximately 830 nm based on K data, in the vicinity of a wavelength of approximately 650 nm based on C data, in the vicinity of a wavelength of approximately 530 nm based on M data and in the vicinity of a wavelength of approximately 400 nm based on Y data. By thus exposing the four colors of K, C, M and Y through the laser beam at the same time, it is possible to shorten a time required for recording to a quarter of that in the recording method shown in FIG. 2.
A latent image is formed in only a portion where the laser beam is irradiated. Therefore, when heat is applied through a heating roller which is not shown, for example, at a next coloring step, the same portion is thermally developed.
The monosheet-shaped recording medium 3 which has been thus exposed with the four colors is accurately removed from the rotary drum 22 for recording through a removing mechanism according to the invention after the exposure and is delivered to a discharge tray.
FIG. 4 shows the specific structure and removing operation of the removing mechanism 42. FIG. 4 is a sectional view showing the removing mechanism 42 in the color image recording apparatus of FIG. 3, and FIGS. 4(a) to 4(e) show the removing operation.
In FIG. 4, the removing mechanism 42 includes a removing roller 62, a removing unit 63 constituted by a removing claw 64 and a metal plate guide 65, moving means 66 and a delivery roller 71.
The removing roller 62 is constituted to come in contact with or remove from the recording drum 34. When the toner sheet 11 or the image receiving sheet 10 is to be removed from the recording drum 34, the removing roller 62 comes in contact with the recording drum 34. Then, the removing roller 62 is rotated in a direction opposite to a direction of rotation of the recording drum 34 (a direction of an arrow shown in a dotted line), and presses the laminated product of the image receiving sheet 10 and the toner sheet 11 from the toner sheet 11 side.
Moreover, the removing unit 63 includes the removing claw 64 and the metal plate guide 65. More specifically, when the removing unit 63 is to remove the toner sheet 11 or the image receiving sheet 10 from the recording drum 34, it comes in contact with the recording drum 34 and delivers the toner sheet 11 or image receiving sheet 10 removed from the recording drum 34 to the delivery roller 71 along the removing claw 64 and the metal plate guide 65 with the rotation of the recording drum 34 while removing a tip of the toner sheet 11 or image receiving sheet 10 through the removing claw 64.
The specific structure of the removing unit 63 is shown in FIG. 5.
FIG. 5 is a view showing the structure of the removing unit 63 in the removing mechanism 42 of FIG. 3, FIG. 5(a) being a simplified sectional view showing the removing unit 63 and FIG. 5(b) being a front view showing the removing unit 63.
In FIG. 5(a), the removing unit 63 includes the removing claw 64 for removing the tip of the toner sheet 11 or image receiving sheet 10 from the recording drum 34, and the metal plate guide 65 fixed to the removing claw 64 through a fixing point 65a. 
The removing claw 64 not only removes the toner sheet 11 or image receiving sheet 10 at the tip thereof but also functions as a delivery guide. When the tip of the toner sheet 11 or image receiving sheet 10 is removed, the removing claw 64 then delivers the toner sheet 11 or the image receiving sheet 10 to the delivery roller 71 together with the metal plate guide 65 while removing the toner sheet 11 or the image receiving sheet 10. The metal plate guide 65 has such a structure as to be extended in a vertical direction with respect to the direction of the rotation of the recording drum 34 as shown in FIG. 5(b), and is provided with a plurality of removing claws 64 at almost regular intervals in a longitudinal direction thereof. The metal plate guide 65 delivers the toner sheet 11 or image receiving sheet 10 removed through the removing claw 64.
When the toner sheet 11 or the image receiving sheet 10 is to be removed from the recording drum 34, the moving means 66 moves the removing unit 63 such that the removing claw 64 comes in contact with the recording drum 34. Moreover, while the delivery roller 71 is rotated in a direction opposite to the direction of the rotation of the recording drum 34 (see FIG. 4(e)), it interposes and delivers the toner sheet 11 or the image receiving sheet 10 from the metal plate guide 65 to the laminate section 46.
Moreover, the recording drum 34 has sucking trenches 22a and 22b for adsorbing and fixing the image receiving sheet 10 and the toner sheet 11 provided on a surface thereof. More specifically, inside air is sucked by means of sucking sources such as an outside air blower and a vacuum pump of a vacuum sucking mechanism which is not shown so that the recording drum 34 sucks, through the sucking trenches 22a and 22b, the image receiving sheet 10 and the toner sheet 11 which are delivered to the surface and holds and fixes them on the surface. FIG. 6 is a partially expanded sectional view showing the recording drum 34.
In FIG. 6, an outermost rectangle is obtained by cutting and expanding the recording drum 34 in an axial direction. Moreover, an inside rectangle indicates the toner sheet 11 to be fed and adsorbed onto the image receiving sheet 10 and a further inside rectangle indicates the image receiving sheet 10 to be adsorbed onto the recording drum 34.
The recording drum 34 is provided with the sucking trenches 22a and 22b for firmly fixing a tip portion of each of the image receiving sheet 10 and the toner sheet 11 which are opened within a range in which the image receiving sheet 10 and the toner sheet 11 on the surface are secured. In general, the toner sheet 11 is larger than the image receiving sheet 10, the image receiving sheet 10 is adsorbed by the sucking trench 22a and the toner sheet 11 is adsorbed by the sucking trench 22b positioned in a larger portion than the image receiving sheet 10. Accordingly, it is possible to prevent the image receiving sheet 10 and the toner sheet 11 from being taken off from the recording drum 34.
Moreover, the removing mechanism 42 can remove the toner sheet 11 or the image receiving sheet 10 by utilizing the sucking trenches 22a and 22b for adsorbing and fixing the image receiving sheet 10 and the toner sheet 11 which are provided on the recording drum 34.
The removing operation of the removing mechanism 42 will be described below in detail with reference to FIG. 4. Since the operation for removing the toner sheet 11 and the image receiving sheet 10 is carried out in the same manner, description will be given to only the removing operation to be carried out for removing the toner sheet 11 from the recording drum 34.
FIG. 4(a): In the case in which the toner sheet 11 is to be removed from the image receiving sheet 10 in the removing mechanism 42, the removing roller 62 first comes in contact with the recording drum 34 which is being rotated in a direction of an arrow shown in a dotted line and presses the laminated product of the image receiving sheet 10 and the toner sheet 11 while being rotated in a direction opposite to the direction of the rotation of the recording drum 34 from the toner sheet 11 side (in a direction of an arrow shown in a solid line). Then, the moving means 66 moves the removing unit 63 in a direction of an arrow shown in a solid line such that the removing claw 64 comes in contact with the recording drum 34 which is being rotated.
FIG. 4(b): When the removing claw 64 comes to a position of the sucking trench 22b for the toner sheet 11 by the rotation of the recording drum 34, the moving means 66 moves the removing unit 62 to cause the removing claw 64 to enter the sucking trench 22b for the toner sheet 11.
FIG. 4(c): The removing claw 64 removes the tip of the toner sheet 11 with the rotation of the recording drum 34. Then, when the tip of the toner sheet 11 is lifted by the removing claw 64, the toner sheet 11 is delivered along the metal plate guide 65 while being removed. In this case, the removing claw 64 also delivers the toner sheet 11 together with the metal plate guide 65 as a delivery guide. Consequently, thermal energy is applied to an image through heat mode exposure so that the bonding force of the toner layer is reduced. Thus, the laminated product of the toner sheet 11 having an image formed as a latent image and the image receiving sheet 10 having the image receiving layer to which the toner sheet 11 is bonded is removed and the image of the toner sheet 11 which is recorded as the latent image is transferred and developed onto the image receiving sheet 10.
FIG. 4(d): When the toner sheet 11 is started to be delivered while being removed, the moving means 66 moves the removing unit 63 to be kept away from the recording drum 34 (in a direction of an arrow shown in a solid line) so that the image receiving sheet 10 can be prevented from being removed through the removing claw 64. Consequently, only the toner sheet 11 can be removed and delivered.
FIG. 4(e): When the tip of the toner sheet 11 is interposed between the delivery rollers 71, the delivery rollers 71 interpose and deliver the toner sheet 11 to the laminate section 46 while being rotated in a direction of an arrow shown in a solid line and holding the tip of the toner sheet 11 delivered along the metal plate guide 65.
By repeating the removing steps 4(a) to 4(e) for the toner sheet 11 having predetermined colors, for example, four colors of KCMY, a full color image is formed on the image receiving sheet 10.
FIG. 7 is a view showing the structure of the removing claw 64 according to the conventional example. FIG. 7(a) is a side view showing the removing claw, FIG. 7(b) is a top view, and FIG. 7(c) is a sectional view showing the removing claw 64 of FIG. 7(a) which is taken along a line 7–7′.
As shown in FIG. 7, the conventional removing claw 64 includes a claw body 64a having a rectangular cross section with a height reduced toward a tip, and a base 64b, and serves to remove, at a tip thereof, a tip of the toner sheet 11 or image receiving sheet 10 and to deliver the toner sheet 11 or image receiving sheet 10 thus removed along a slant face. A width W in a cross direction of the claw body 64a is 3 [mm]. Moreover, the base 64b has a width which is reduced toward a tip and is equal to the width of the claw body 64a at the tip thereof.
Pressure at a surface of the removing claw given from the sensitive material is about 2 Kpa in accordance with the weight of the recording media and the number of the removing claws.
In the removing mechanism 42 of the color image recording apparatus 30 according to the conventional example, when the toner sheet 11 having the tip removed through the removing claw 64 is to be delivered to the delivery roller 71, the toner sheet 11 comes in contact with the removing claw 64. However, the removing claw 64 has a small face to come in contact with the toner sheet 11 and has both ends of an upper side provided at a right angle. Therefore, a material of the toner sheet 11 is rubbed and shaved by the surface of the removing claw 64 and the corners of both ends of the upper side. In particular, if a face pressure of the toner sheet and the removing claw (a pressure of the contact face) is high, more shavings are generated.
The shavings of the material stick onto the recording drum 34 and the image receiving sheet 10. As a result, there is a problem in that image defects (image unevenness, a void and a white ring) are generated on a finished image.
In order to solve such a problem, the present inventor has presented, as a prior invention, a printer mechanism in which a delivery speed of the delivery roller 71 is set to be higher than that of the recording drum 34 for the toner sheet 11 to eliminate the deflection of the toner sheet 11 between the recording drum 34 and the delivery roller 71 and the removing claw 64 is moved to the outside of a delivery path for the toner sheet 11 to prevent the contact of the removing claw 64 with the toner sheet.
However, the toner sheet 11 comes in contact with the removing claw 64 before it is removed and interposed between the delivery rollers 71. Consequently, there is a problem in that image defects are generated at a ratio of one to several tens.